I've whacked a few of these together for mates. Last one used a selection of pulleys off a d21 terrano, a Nissan pulsar wiper motor and an oil drum. A car battery doesn't quite have the legs to do an entire roast, but if you put a charger on it it works a treat.
Don't forget to put a rack in up top if it's enclosed, baked potatoes nom nom nom
Makes me hungry just thinking about it.
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